50% is the change from 520 to 780
Calculation steps:
[( 780 - 520 ) ÷ 520] x 100 = 50%
Formula
Percentage change = [(780 - 520) / 520] x 100
Subtract the new number by the original number
780 - 520 = 260
260 ÷ 520 = 0.5
0.5 x 100 = 50%
Example